Retroreflective materials have been developed for use in a variety of applications, including road signs, license plates, footwear, and clothing patches to name a few. Retroreflective materials are often used as high visibility trim materials in clothing to increase the visibility of the wearer. For example, retroreflective materials are often added to protective garments worn by firefighters, rescue personnel, EMS technicians, and the like.
Retroreflectivity can be provided in a variety of ways, including by use of a layer of tiny glass beads or microspheres that cooperate with a reflective agent, such as a coated layer of aluminum. The beads can be partially embedded in a binder layer that holds the beads to fabric such that the beads are partially exposed to the atmosphere. Incident light entering the exposed portion of a bead is focused by the bead onto the reflective agent, which is typically disposed at the back of the bead embedded in the binder layer. The reflective agent reflects the incident light back through the bead, causing the light to exit through the exposed portion of the bead in a direction opposite the incident direction.
Retroreflective materials can be particularly useful to increase the visibility of fire and rescue personnel during nighttime and twilight hours. In some situations, however, firefighter garments can be exposed to extreme temperatures during a fire, causing the retroreflective material to trap heat inside the garment. Under certain conditions, the trapped heat can result in discomfort or even bums to the skin of the firefighters
In particular, moisture collected under the retroreflective material may expand rapidly when exposed to the extreme temperature from the fire. If the expanded moisture is unable to quickly permeate through the retroreflective material, the firefighter can be exposed to extreme temperatures. In some cases, this can result in steam bums on the skin of the firefighter underneath the portions of the garment having the retroreflective material. Conventional retroreflective materials, including perforated retroreflective materials generally exhibit this phenomenon. For example, conventional perforated retroreflective materials include standard retroreflective trim having needle punched holes, laser punched holes, slits, or relatively large holes made with a paper punch.